Class: SerialProtocol::RCA2006Simple

Inherits:
RCA2006
  • Object
show all
Defined in:
lib/protocol/rca2006.rb

Constant Summary

Constants inherited from RCA2006

SerialProtocol::RCA2006::STARTBYTES, SerialProtocol::RCA2006::TYPE

Instance Method Summary collapse

Methods inherited from RCA2006

#on_raw_receive, #on_raw_send, #receive_handler

Constructor Details

#initialize(send_callback, receive_callback, options = {}) ⇒ RCA2006Simple

Returns a new instance of RCA2006Simple.



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# File 'lib/protocol/rca2006.rb', line 128

def initialize(send_callback, receive_callback, options = {})
  @type = :data_no_crc
  @counter = 0
  super
end

Instance Method Details

#add_char_to_packet(char) ⇒ Object

Big and ugly state machine that does most of the work



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# File 'lib/protocol/rca2006.rb', line 153

def add_char_to_packet(char)
  @state = :first_checksum if (@state == 0)
  case @state
  when :first_startbyte
    @data = ""
    @state = ((char == STARTBYTES[0]) ? :second_startbyte : :first_startbyte)
  when :second_startbyte
    @state = (char == STARTBYTES[1]) ? :length : 
      # special case: first startbyte is repeated
      (char == STARTBYTES[0] ? :second_startbyte : :first_startbyte)
  when :length
    @length = char
    @state = @length
  when Integer
    @data << char
    @state -= 1
  when :first_checksum
    @checksum = (char << 8)
    @state = :second_checksum
  when :second_checksum
    @checksum = @checksum + char
    @state = :first_startbyte

    crc = ("" << @length << @data).crc_xmodem
      # received a valid packet
      
    if @type == :data || @type == :data_no_crc
      if @checksum == crc
         
        receive_handler(@type, @counter, @data,@checksum)
      else
        # send NACK and discard packet
        raise ChecksumMismatch, "ChecksumMismatch, expected #{crc}, was #{@checksum}"
      end
    else
      # the packet is ACK, NACK or unknown, call receive-handler
      # data may be mangled since the checksum is not checked
      #
      receive_handler(@type, @counter, @data, @checksum)
    end
  end        
end

#send_packet(data, options = {}) ⇒ Object

Wrap a string into a packet

the options-hash can be used to override the default packet format



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# File 'lib/protocol/rca2006.rb', line 138

def send_packet(data, options = {})
  str = data.to_s
  checksum = options[:checksum] || ("" << str.length << str).crc_xmodem

  @raw_send_callback.call(:data_no_crc, 0, data, checksum) if @raw_send_callback
  
  p = "" << STARTBYTES << str.length << str << [checksum].pack("S").reverse

  # send the packet, using the callback
  #
  @send_callback.call(p)
end